Japanese Patent No. 3123424 discloses conventional article transporting facilities, which comprise a plurality of article holding sections, i.e. the storages of article storing racks and the loading sections of a conveyer, a stacker crane as a movable body for freely transferring articles among the article holding sections, a fire detecting means for detecting fire which occurs in an article held in the article holding sections, and a fire extinguishing means for freely spraying a fire extinguishing agent.
This patent does not give a detailed explanation of the traveling control of the movable body; however, a movable body for conveying articles, such as a stacker crane, generally uses such a technology in which an optical ranging means is provided to detect a distance between the reference position for travelling and the movable body on the traveling path by projecting a measurement light along the traveling path, making the movable body travel to the target travel position on the traveling path in accordance with the detected distance by the optical ranging means, as mentioned in Japanese Patent Preliminarily Publication No. 2009-161321.
As disclosed in the publication, the optical ranging means normally uses a laser light beam as the measurement light. In this publication, a reference position on the ground side is set in the vicinity of the end portion of the travelling path; a reflection plate is provided at the reference position to reflect the laser light beam from the laser ranging meter, which is provided on the movable body side. A laser light for ranging is projected from the laser ranging meter to the reflection plate and the laser light reflected back by the reflection plate is received by the laser ranging meter to detect the distance between the meter and the reflection plate.